a) Field of the Invention
This invention relates to a plant cultivation mat (or grass growing mat) to be laid on the roof top, veranda, terrace, etc. of buildings (in particular, an artificial ground) for growing various plants such as, especially, ground-covering plants like lawn, etc., grasses, flowers, vegetables, and so forth, and to a water-storing tray for such plant cultivation mat.
b) Description of Prior Arts
It has been the conventional practice that, in the case of cultivating or growing plants at a location having a flat laying surface such as roof top, veranda, terrace, etc. of a building, a water-prevention layer and a root-protection layer are formed (or a water-prevention sheet or a root-protection sheet is laid) over such flat laying surface, and then soil is spread over the layer or sheet to cultivate ground-covering plants such as lawn, grasses and shrubs, vegitables, and so forth (vide: for example, laid-open gazette of Japanese Patent Application No. 4-99411).
With the abovementioned method of spreading soil on the artificial ground, however, there arises necessity for providing plant cultivation arrangement such as water-prevention layer, root-protecting layer, etc. , which give rise to various problems such that the equipment can hardly be adopted in those existing buildings, and, even when it is adopted in new buildings, cost to be borne would become prohibitively high. In addition, for the installation of the abovementioned plant cultivation arrangement, a large-scaled working would become necessary with the consequence that much time and labor are needed.
On the other hand, the service life of the water prevention layer is in general said to last from 10 to 15 years. Besides its service life, when unexpected damages occur to the water-prevention layer and the laying surface of the plant cultivation mat due to the plant cultivation work, it becomes also necessary to remove the plants under cultivation and the soils for cultivation with a view to repairing such water prevention layer against its water leakage. Again, enormous amount of time and labor are needed for this removing work.